For this, you will need to download the free software TCPView.
The program does not need to be installed; you can simply unzip it in a directory of your choice along with the help file and run the executable file Tcpview.exe.
Some minor tweaks:
In the menu View, set Update Speed to one second. This allows, as you may have guessed, to refresh the list every second.
- In the Options menu:
- Resolve Addresses allows you to see the name of the remote server to which you are connected rather than its IP.
- Show Unconnected Endpoints also shows inactive connections. Since we are focusing on the connections that actually use the bandwidth, it is recommended to uncheck this option.
- Always On Top window allows TCPView to always be above the others
- Font allows you to change the font of the application, do not bother to touch it if you can read.
How to use it?
-When you right click on a connection:- Close connection closes the selected connection, and those who depend on them. If you see an unknown program using and abusing of your connection, this option will disconnect it immediately. (However note that is not to be excluded that it can reconnect immediately, or later)
- End Process is more delicate. Indeed, it closes the program that uses the connection, instead of just disconnecting it as happens in the previous option.
- Process Proprieties shows the location on the hard disk of the program using the connection.
- Connections that have just been created are shown in green
- Connections that are changing server or port are shown in yellow.
- Closing connections are shown in red.
Finding the culprit
From the list of processes,click on Rcvd Bytes to sort it in Descending order .This column represents the number of bytes the corresponding process has downloaded.The Sent Bytes and the Rcvd Packets columns will also help you to identify the culprit among your applications.To deny an application from continuing using your internet connection , right-click on the specific process and click End Process .
You can also use this TCPview to hunt down unwanted programs , malware , spyware by analyzing the process names and their corresponding bytes being transferred.